To provide infective larvae and adult worms of the filarial parasite, Brugia Malayi, for studying human immunity to lymphatic filariasis, a disease which causes elephantiasis in humans. The high quality and well standardized parasite materials required under this contract are necessary to maintain the progress of on-going carefully controlled research studies being conducted by NIH. Colonies of the mosquito Aedes aegypti, (Liverpool strain) are also required to be maintained for the production of the ineffective larvae.